EPR spectroscopy will be utilized to study structure, function, and dynamics of biological macromolecules. Ikeda-Saito will measure EPR of metal centers in heme enzymes to delineate active site structure. Gerken will elucidate the nature of viscoelastic properties of mucous glycoproteins by EPR characterization of dynamics and conformation of the spin-labeled proteins. Ikebe will study the possible change in the coordination of the metal ion to active site of myosin and myosin light chain kinase in relation to their activities by EPR measurements of Mn(II)- ATP (ADP)-protein complexes. EPR signal of the spin-label attached to the carbohydrate groups in IgG will be used to characterize the Clq binding site in IgG by Jentoft. Maguire will study interaction of the Mg(II) surrogates Co(II), Ni(II), or Mn(II) with metal binding sites of the unique Mg(II) transport protein from Salmonella typhimurium by EPR measurements. Aims of these projects are best achieved by EPR or combination of EPR with other techniques. The requested EPR spectrometer will have a significant impact on progress of these research projects listed in this proposal.